Struct AVCompositionTrackSegment

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pub struct AVCompositionTrackSegment { /* private fields */ }

Available on crate features AVAssetTrackSegment and AVCompositionTrackSegment only.

Expand description

Apple’s documentation

Implementations§

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impl AVCompositionTrackSegment

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pub unsafe fn compositionTrackSegmentWithURL_trackID_sourceTimeRange_targetTimeRange( url: &NSURL, track_id: CMPersistentTrackID, source_time_range: CMTimeRange, target_time_range: CMTimeRange, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Returns an instance of AVCompositionTrackSegment that presents a portion of a file referenced by URL.

Parameter URL: An instance of NSURL that references the container file to be presented by the AVCompositionTrackSegment.

Parameter trackID: The track identifier that specifies the track of the container file to be presented by the AVCompositionTrackSegment.

Parameter sourceTimeRange: The timeRange of the track of the container file to be presented by the AVCompositionTrackSegment.

Parameter targetTimeRange: The timeRange of the composition track during which the AVCompositionTrackSegment is to be presented.

Returns: An instance of AVCompositionTrackSegment.

To specify that the segment be played at the asset’s normal rate, set source.duration == target.duration in the timeMapping. Otherwise, the segment will be played at a rate equal to the ratio source.duration / target.duration.

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pub unsafe fn compositionTrackSegmentWithTimeRange( time_range: CMTimeRange, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Returns an instance of AVCompositionTrackSegment that presents an empty track segment.

Parameter timeRange: The timeRange of the empty AVCompositionTrackSegment.

Returns: An instance of AVCompositionTrackSegment.

Source

pub unsafe fn initWithURL_trackID_sourceTimeRange_targetTimeRange( this: Allocated<Self>, url: &NSURL, track_id: CMPersistentTrackID, source_time_range: CMTimeRange, target_time_range: CMTimeRange, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Initializes an instance of AVCompositionTrackSegment that presents a portion of a file referenced by URL.

Parameter URL: An instance of NSURL that references the container file to be presented by the AVCompositionTrackSegment.

Parameter trackID: The track identifier that specifies the track of the container file to be presented by the AVCompositionTrackSegment.

Parameter sourceTimeRange: The timeRange of the track of the container file to be presented by the AVCompositionTrackSegment.

Parameter targetTimeRange: The timeRange of the composition track during which the AVCompositionTrackSegment is to be presented.

Returns: An instance of AVCompositionTrackSegment.

To specify that the segment be played at the asset’s normal rate, set source.duration == target.duration in the timeMapping. Otherwise, the segment will be played at a rate equal to the ratio source.duration / target.duration.

Source

pub unsafe fn initWithTimeRange( this: Allocated<Self>, time_range: CMTimeRange, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Initializes an instance of AVCompositionTrackSegment that presents an empty track segment.

Parameter timeRange: The timeRange of the empty AVCompositionTrackSegment.

Returns: An instance of AVCompositionTrackSegment.

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pub unsafe fn isEmpty(&self) -> bool

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn sourceURL(&self) -> Option<Retained<NSURL>>

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn sourceTrackID(&self) -> CMPersistentTrackID

Available on crate feature objc2-core-media only.

This property is not atomic.

§Safety

This might not be thread-safe.

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impl AVCompositionTrackSegment

Methods declared on superclass AVAssetTrackSegment.

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pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

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pub unsafe fn new() -> Retained<Self>

Methods from Deref<Target = AVAssetTrackSegment>§

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pub unsafe fn timeMapping(&self) -> CMTimeMapping

Available on crate feature objc2-core-media only.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn isEmpty(&self) -> bool

This property is not atomic.

§Safety

This might not be thread-safe.

Methods from Deref<Target = NSObject>§

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pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

§Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

§Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

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pub unsafe fn get_ivar<T>(&self, name: &str) -> &T
where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

§Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

Source

pub fn downcast_ref<T>(&self) -> Option<&T>
where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

§Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

§Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

§Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

§Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}